pkg/tools/btf/check.go

// Licensed to Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Apache Software Foundation (ASF) licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package btf

import (
	"debug/elf"
	"fmt"

	"github.com/apache/skywalking-rover/pkg/tools/host"
	"github.com/apache/skywalking-rover/pkg/tools/operator"
	"github.com/apache/skywalking-rover/pkg/tools/path"
)

func ExistKernelBTF() (string, error) {
	if path.Exists(host.GetFileInHost("/sys/kernel/btf/vmlinux")) {
		return "/sys/kernel/btf/vmlinux", nil
	}

	uname, err := operator.GetOSUname()
	if err != nil {
		return "", err
	}

	// use same list of locations as libbpf
	// https://github.com/libbpf/libbpf/blob/9a3a42608dbe3731256a5682a125ac1e23bced8f/src/btf.c#L3114-L3122
	locations := []string{
		"/boot/vmlinux-%s",
		"/lib/modules/%s/vmlinux-%[1]s",
		"/lib/modules/%s/build/vmlinux",
		"/usr/lib/modules/%s/kernel/vmlinux",
		"/usr/lib/debug/boot/vmlinux-%s",
		"/usr/lib/debug/boot/vmlinux-%s.debug",
		"/usr/lib/debug/lib/modules/%s/vmlinux",
	}

	for _, loc := range locations {
		_, err := elf.Open(host.GetFileInHost(fmt.Sprintf(loc, uname.Release)))
		if err == nil {
			return loc, nil
		}
	}
	return "", fmt.Errorf("could not found")
}